Run the Horizon unit tests both with Django 1.4 and 1.5

[Julie Pichon]

Since we'd like to support both Django 1.4 and 1.5, we should run the CI tests with both environments. After chatting with the infra folks, we should create a new tox environment that runs the tests in a Django 1.4 environment. Once we have something like 'tox -r -e py27dj14' working, infra can help us add a job to run that in the check and gate pipelines.

We probably need to do some pinning magic. We could have a tox environment that preinstalls 1.4 and then calls the other [however I seem to recall that Django ended up being upgraded to the latest when I tried similar things in my local venv]. We may need to do some pip-requires mangling/adjustement in tox for the new environment.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/30751

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/30751
Committed: http://github.com/openstack/horizon/commit/a6d72d7bfed60447c428ff17acf7f33dbfce1843
Submitter: Jenkins
Branch: master

commit a6d72d7bfed60447c428ff17acf7f33dbfce1843
Author: Julie Pichon <email address hidden>
Date: Tue May 28 15:43:34 2013 +0100

    New tox environment for testing with Django 1.4

    First step toward resolving bug #1183863

    Change-Id: Id7dbf011968ea817c547cd020fbf697f7b538181

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/32884

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/32884
Committed: http://github.com/openstack-infra/config/commit/ecf346a668631e4f560949686c2669a0c2d281bd
Submitter: Jenkins
Branch: master

commit ecf346a668631e4f560949686c2669a0c2d281bd
Author: Jeremy Stanley <email address hidden>
Date: Thu Jun 13 13:10:56 2013 +0000

    Run Horizon unit tests with Django 1.4 too.

    Fixes bug 1183863.

    * .../jenkins_job_builder/config/horizon.yaml: Add a new
    gate-horizon-python27-django14 job which uses a separate tox
    environment to force Django 1.4 instead of 1.5.

    * .../zuul/layout.yaml: Run gate-horizon-python27-django14 on
    horizon's master branch in the check and gate pipelines. Earlier
    horizon stable releases pinned Django to 1.4 anyway and do not need
    this additional job.

    Change-Id: Ibdf273ff35124d33eeae97f7b4749c15b9c980f0